Lecture 3

Question 1

Hydrocarbons

Answer 1

Saturated vs. Unsaturated:
- Sat = joined by a single carbon-carbon bond (Alkanes)
- Unsat = carbon-carbon multiple bonds (Alkenes, alkynes and aromatics)

Aliphatic:
- Alkanes, alkenes and alkynes
Aromatics

Question 2

Aliphatic Hydrocarbons

Answer 2

The carbon to carbon can be;
- single (‘’ane’’
- double (“ene”)
- triple (“yen”)

NOTE: Hydrogen can only make a single bond. The double and triple bonds are present between two carbons.

Question 3

Homologous Series

Answer 3

Millions of different organic compounds, classified into different families with similar formulae and properties.
Each family of OrgComps. Is called a Homologous Series
It is a family of compound with the dame general formula, same functional group and similar chemical properties.

Question 4

Homologous series - Characteristics

Answer 4

1. The same general formula
2. The same functional group (FG is an atom or group of atoms that gives characteristic chemical properties)
3. Similar chemical properties but varying reactivity
4. Physical properties vary gradually along series

Question 5

Geometry of carbon

Answer 5

1. The carbon atom forms bonds in a tetrahedral structure with a bond angle of 109.5*
2. As carbon-to-carbon bond gangles are 109.5, so a chain of carbon atoms make a zigzag pattern.
3. The unbranched chain of carbon atoms is usually simplified in a way that looks like a straight chain, but is actually a zigzag.

Question 6

Branching

Answer 6

• In unbranched (continuous) chain, atoms are bonded one after another
• In branched chain, some atoms form branches off the longest chain
• Branched alkanes are named by indications the branch attached to the principal chain, branched, known as substituents, are named by taking the name of an alkanes and replacing it with a suffix with yo - for example, methyl, ethyl and so on. The general term for an alkanes with functions as a substituent is alkyl.

Question 7

Alkyl groups

Answer 7

Methyl group = -CH3

Ethyl group = -C2H5

Propyl group = -C3H7

Question 8

Carbon classification

Answer 8

Carbon compounds in alkanes and other compounds are classified by a number of other carbons directly bonded to them.

Primary carbon - a carbon bonded to on carbon atom
Secondary carbon - a carbon bonded to two carbon atoms
Tertiary carbon - a carbon bonded to three carbon atoms
Quaternary carbon - a carbon bonded to four carbon atoms

Question 9

Naming Compunds

Answer 9

IUPAC

All naming of organic molecules follows the IUPAC system.

Question 10

IUPAC rules

Answer 10

1. Find the longest carbon chain. That gives the parent name., e.g. five carbon chain = pent(…)
2. The branching (if any) goes from the lowest number to highest. E.g. position 2 instead of position 4.
3. Name the group (if any) joined to the chain and state the number of the carbon is is joined on.
4. If the chain has 2 or more identical groups joined to it, prefixes like: di-, tri-, tetra-, are used to indicate number of groups present.
5. If the chain has two or more different groups joined to it, the groups are written in alphabetical order. E.g. ethyl before methyl.